The Stalker: An Easy DIY Double Tracker  [documentation]

Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
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Ripthorn
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Post by Ripthorn »

I've been on a bit of a delay kick (see EchoWreck and T60) and thought "why not try a double tracker?" However, one reason there are so few of them out there is that the PT2399 doesn't do short enough delay times for a lot of double tracking. It's got a 29 ms or so minimum time. I was repairing a CE-5(t) that uses the ES56028 and found it had very low delay times, but it's a 40 pin chip. Turns out there is a 16 pin ES56033. I bought five on Aliexpress to try out and the Stalker came out of it.

The ES56033 has a minimum delay time of 14 ms, which works quite well for a minimum delay time in a double tracker. I designed the Stalker with a ~55ms max delay time so that it just gets into slap back territory. It has controls for time (distance), mix (stealth), and modulation (creepy) as well as a switch that disables the modulation LFO. The modulation is very mild, as the typical "pin 2 hack" or other modulation schemes used on a PT2399 don't work on the ES56033 due to how delay time is set.

Apart from pin assignments, the ES and PT are fairly similar in architecture. For a more detailed explanation on how it works and design choices, I have a full on article at the webpage for this project at https://scientificguitarist.wixsite.com ... he-stalker. It also has build documentation, schematic, a perf board layout, and suggestions on how to do things like stereo output, etc. Here is a quick and dirty demo video:



EDIT: Why does youtube embed hate me? I can't get it working for the life of me...

Moderator: The Youtube BBcode expects the full link. Sorry about that.
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cspar
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Post by cspar »

Well done.

Seems like it might work well with slide and I could see myself using this more often than a PT2399 based delay so it's definitely going on my build list.

Your T60 demo sounds incredible but now I'm really curious about the reverb potential of the ES56033.

It's datasheet sure is sparse but if I'm reading it correctly it seems that it has a little less distortion and noise than a PT2399.

How variable were the chips in your order compared to a similar order of PT2399's?
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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Ripthorn
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Post by Ripthorn »

I haven't checked the ES56033's for variability, but they should work for a reverb. However, they modulation scheme I used in the T60 won't work on the ES56033 because how it sets delay time is a little different. Thus I don't think the reverb with an ES56033 will be as rich of a sound, as the subtle modulation helps give the impression of a real space.

In addition to the modulation issue, the shorter delay time available on the ES56033 isn't required for a reverb. With a typical speed of sound, 14 ms would correspond to a first reflection distance of only 4.8 meters. This would feel like a relatively small space, which may be fine, but if you look at how I configured the T60, the first "reflection" time is around 35 - 40 ms.

However, don't take the above as reasons to not try it, simply take them as things to keep in mind if you do try it. I'm all for trying new stuff, as some of my recent projects have shown.
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Post by ppluis0 »

Hi Ripthorn,

There is a pin to pin equivalent of PT2399 named HT8970: https://www.datasheetq.com/datasheet-do ... tek/HT8970

The main difference is that this IC has only 20Kb of internal RAM (compared to 44Kb of PT2399) but the time tables on both datasheets present the same numbers. :scratch:

Personally I think that the delay times would be shorter than the published judging the reduced RAM capacity, but I don't have means to test or measure this parameter.

Hope this information can be of interest to you.

Cheers,
Jose

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Ripthorn
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Post by Ripthorn »

I did look at that chip, but it was a little harder for me to find, and the documentation I found seemed to indicate it was an older chip. That may not be true, but boss uses the bigger brother of the es56033, so the parts/ manufacturer should be relatively robust.
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Ben N
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Post by Ben N »

Downloadable zip file is "invalid" and won't open, per my computer.

Cancel that: You just have to use the "Download file" button, rather than right-click/download. Thanks for a very nice package!

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caspercody
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Post by caspercody »

I have created a vero board layout, and made this pedal. It is a great pedal.

I also did his smaller version, The Shadow.

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Post by Ichabod_Crane »

Caspercody, did you share your layouts, too?

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Post by caspercody »

Here you go. Not the best layout's, but they worked for me. I made changes after I made the boards and realized I had errors, hence the long jumpers. The PDF layout's are exact size to put on top of vero boards and use as a guide. I tape them on the vero board and insert the parts on top of the paper.
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Post by Ichabod_Crane »

Thanks.
It's a strange effect.

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Ripthorn
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Post by Ripthorn »

Glad you guys like it. I have done an updated version of the Stalker with modified LFO control so that you can get even weirder effects out of it. I'll have to check whether that's in the latest package or not.

caspercody, thanks for the vero layouts. I don't do vero for anything, so creating layouts and the typical best practices/logic are a little foreign to me.
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Post by caspercody »

Thank you for the circuits!! I have been searching for a DIY circuit to do a similar doubler effect like the Rockman X100 chorus/doubler when I found your web site. But I would love a similar project to the Rockman chorus

I got some of those big brother chips, waiting for your next projects.

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Ripthorn
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Post by Ripthorn »

Once I resolve the LFO to give me the shape that I want, I've got a through zero flanger design using the 56028 otherwise ready to rock. Technically it's complete, but the LFO shape is a little more asymmetric than I want. I just need to sit down and bang it out.
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Post by bmxguitarsbmx »

You're killing it Rip! Thanks for all your efforts and well documented projects!

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